NEW FORWARD CLUTCH LO & REV. WAVED PLATES

SUBJECT: NEW PLATES - 4TH CLUTCH REACTION, FORWARD CLUTCH, LO AND REVERSE WAVED

MODELS AFFECTED: 1980-91 ALL MODELS WITH 3T40 (THM 125C) 4T60 (THM 440T4) OR 4T60E

BULLETIN COVERS: (Figure 1)

New 4th clutch reaction plates for the Hydra-Matic 4T60 and 4T60-E transaxles; and new forward clutch and lo and reverse waved plates for the Hydra-Matic 3T40. All three new plates will have blackened edges, and the flat surfaces will have some lightly blackened areas. The new plates are made with a new process to aid manufacturing. A by-product of this new process is that the edges will be blackened, and the flat surfaces will have some lightly blackened areas. Figure 1 shows an example of a 4th clutch reaction plate with blackened areas and edges. The forward clutch and lo and reverse clutch waved plates will have similar markings.

SERVICE PROCEDURE:

Replace the 4th clutch reaction plates if severely warped. Replace the 4th clutch reaction plates, forward clutch waved plate, or the lo and reverse waved plates if they have obvious large overheated, discolored areas that mate to the fiber material plate. Heat discoloration on the plate back side (non-fiber mating surfaces) should be considered normal, unless the plate is warped.

DATE OF PRODUCTION CHANGE:

Beginning July 25, 1990 (Julian Date 206), some 1991 Hydra-Matic 4T60 and Hydra-Matic 4T60-E transaxles were built with the new 4th clutch reaction plates. As of September 10, 1990 (Julian Date 253) all models should have the new reaction plates.

Beginning October 10, 1990, (Julian Date 283) all 1991 Hydra-Matic 3T40 transaxles are being produced with the new forward clutch and lo and reverse waved plates.

SERVICE PARTS INFORMATION:

The new parts will be available when the previous parts are depleted.

SERVICE MANUAL REFERENCE:

Refer to the appropriate Service Manual for proper disassembly and assembly procedures.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.